1. Field of the Invention
The invention relates generally to photochemical processes and, more particularly, to an air purifier and method that utilize UV radiation.
2. Background of the Invention
Photochemical reactions are chemical processes initiated by absorption of energy in the form of visible, infrared, or ultraviolet radiation. Photochemistry is different from many other forms of chemistry because if an atom or molecule absorbs energy from a beam of light, it gains far more energy than it could by other methods, such as heating. Consequently, photochemical processes are extremely efficient for the conversion of energy from light into chemical energy.
Many natural processes are photochemical. Ozone is produced in nature by the action of sunlight on oxygen molecules. In the stratosphere at altitudes of about 25 km, very high-energy (very short wavelength) ultraviolet light converts diatomic oxygen (O.sub.2) into ozone (O.sub.3). In other words, sunlight breaks down some of the oxygen molecules into atoms, which combine with other oxygen molecules to produce ozone:O+O2═O3 
Such an expression is, of course, over-simplified because additional particles are typically involved that absorb some of the heat released during the process, and because ozone is quite unstable and will itself interact with light, alkenes, etc.
This tri-atomic form of oxygen formed naturally in the upper atmosphere by a photochemical reaction with solar ultraviolet radiation is commonly referred-to as the ozone layer. This protective layer absorbs harmful solar ultraviolet radiation and prevents the radiation from passing through, thereby protecting the Earth from these damaging rays. This process decomposes and neutralizes ozone which is then replaced by new ozone created by ongoing photochemical reactions. Ozone is also measured in trace amounts in the lower atmosphere and is used by Mother Nature to purify and deodorize the air.
Ultraviolet (UV) lamps may be used to create ultraviolet energy and ozone by the same photochemical process. By emitting ultraviolet rays into the air, the resultant ozone may be used for air purification. Pure ozone is very caustic and breaks down (oxidizes) any gas it comes in contact with. The target gas or substance (e.g., smoke contaminants) is broken into component parts and is destroyed. As a result, odors are removed from rooms, including those odors trapped in carpeting and drapes. Ozone used for this purpose must be replenished because the ozone molecule is unstable and decomposes after only a short time. For example, a given quantity of ozone dispersed into a room typically will completely dissipate within fifteen to twenty minutes.
Although air purification systems for generating ozone are known, such are not optimized for adaptation to different applications and/or conditions.